A number of prior art automobile sunshields are well-known for use in shielding the interior of an automobile from unwanted heat and sunlight. These sunshields may be positioned against an interior window surface, but are typically positioned against the windshield because of the difficulty of retaining these sunshields against the other window surfaces.
One example is U.S. Pat. No. 4,202,396 to Levy, which illustrates a folding cardboard sunshield. The sunshield is provided with creases or folds so that individual panels are formed and may be stacked in an accordion-like manner for storage. Although Levy describes the sunshield as being retained against a window surface by a number of methods, including the use of hooks and clamping the sunshield between the side window and door frame, the most common and practical way is to retain the sunshield in position against a windshield by the two visors adjacent the ceiling of the passenger compartment. However, even when it is held against the windshield, this sunshield tends to return to the folded position and therefore does not effectively cover the entire windshield.
Another example is U.S. Pat. No. 5,024,262 to Huang, which illustrates a collapsible sunshield which is a sheet material supported by a single resilient loop along its borders. This sunshield may also be retained in position against a windshield by the two visors. This sunshield provides better coverage for the windshield than the sunshield described in U.S. Pat. No. 4,202,396 to Levy. However, since its single loop must be wide enough to cover the entire windshield, the sunshield is necessarily very wide and bulky, which makes it very difficult for an individual to perform the folding steps needed to collapse it to a smaller size.
A further example is illustrated in my earlier U.S. Pat. No. 4,815,784 to Zheng. This sunshield provides two resilient loops, each covered by a sheet material and connected by an interconnecting fabric, with the two loops foldable upon each other to make it easier for the individual to collapse the combined two loops into a smaller size. Each resilient loop portion of the sunshield may be retained in position against the windshield by one of the two visors. However, each loop must be carefully positioned against the windshield and then retained by a visor; otherwise, this sunshield will not be effective in covering the entire windshield. This is because the two loops are separate and are only connected by the interconnecting piece of fabric, so that both loops must be manually positioned against the windshield and manually spread out to cover the entire windshield.
A problem associated with each of these sunshields is that they require the use of the two visors to effectively retain them in position against the windshield. Although Huang teaches in his U.S. Pat. No. 5,024,262 that the one-loop sunshield may be held against the windshield by the spring forces of the loop only, this method has not proven effective and the use of the two visors is still required for effective operation. Thus, the above-described sunshields are not easily adapted for use with side windows or rear windows, and are rendered ineffective for use in covering the windshield if one or both visors of the automobile are either not deployed properly or inoperable. Even if these sunshields are equipped with a conventional attachment device, such as suction cups, for example, for attaching the sunshield to the side or rear windows, the size and weight of the sunshield will typically require several such attachment devices to effectively retain the sunshield against the window without any further assistance from another mechanism. If insufficient suction cups or similar attachment devices are provided, the sunshield will sag at certain locations, thereby allowing heat and sunlight to enter the interior of the automobile.
Thus, there still remains a need for an automobile window sunshield which effectively covers the entire automobile window and blocks sunlight and heat, is adapted for convenient use with any of the automobile windows, is simple in construction and inexpensive to manufacture, and may be conveniently stored.